1. FIELD OF THE INVENTION
The present invention relates to an improved power supply for providing power to display devices.
2. Prior Art
The use of power supplies as energy sources for monitors, computers and other types of electrical devices is well known in the prior art. Power supplies can be classified based upon their topologies. Among the various types of topologies, the flyback or blocking oscillator topology is widely used for low power applications. The topology is popular because it is relatively simple, requires few components, provides multiple regulated outputs from a single supply, etc.
U.S. Pat. No. 4,812,959 describes a blocking oscillator type power supply. The power supply is synchronized to run at the frequency of a display monitor. When synchronized, the power supply operates as a fully reset fixed frequency flyback converter. The power supply includes a drive winding, on the primary side of its power transformer, that provides drive signals to the base electrode of the switching transistor. A feedback loop with a control circuit interconnects the secondary side of the power transformer to the primary side. The feedback loop and control circuit regulate the output voltage of the power supply.
U.S. Pat. Nos. 4,467,406 and 4,745,535 describe ringing choke-type DC/DC converters in which a flyback winding on the primary side of the power transformer is used to control the output voltage on the secondary side of the transformer.
Even though the described prior art power supplies work well for their intended purposes, they have inherent deficiencies which make them inappropriate for use on certain types of devices. There are several areas, such as the consumer electronic industry, that are highly competitive and sub-assemblies, including power supplies, must be low-cost and very reliable. In addition, most electronic devices, such as monitors, is packaged in relatively small frames and space for sub-assemblies are very limited. Finally, most consumer electronic devices are high volume and, therefore, it is desirable to provide sub-assemblies which can be easily manufactured.